The Pointer_stringify() function is deprecated and has a couple of
issues because it tries to guess the encoding of the buffer. In some
cases it can ignore the length parameter which could end up in
inconsistencies.
Switch to UTF8toString() that takes a length parameter and respects,
that way we don't need to allocate an additional byte for a NULL byte.

This patch adds the Olm header files to the manifest, this results in
the header files being added to source distributions of the python-olm
module.
The headers are required to build the module. Including them in the
source distribution is the easiest way to make sure that builds from the
source distribution will succeed provided that the Olm C library is
already installed.
Signed-off-by: Damir Jelić <[email protected]>

This patch adds bindings to the PK part of the Olm library contained in
the pk.h header file.
Encryption, decryption as well as pickling/unpickling of the decryption
object is supported.
Signed-off-by: Damir Jelić <[email protected]>

Typing is part of standard library from python 3.5 and from python 3.7
onwards trying to install it results in an error.
This patch disables typing installation on python versions that are
newer than 3.5.
Signed-off-by: Damir Jelić <[email protected]>